Optical fiber connector

ABSTRACT

An optical fiber connector comprises: a positioning housing that has a recessed open end; a positioning cover that is formed with at least two first grooves and at least two second grooves; and at least two terminal plugs, each of which has a plug housing and an end sleeve. The positioning cover is detachably mountable on the positioning housing between first and second positions relative to the positioning housing to cover the recessed open end. The end sleeves are respectively fitted into the first grooves when the positioning cover is disposed at the first position, and are respectively fitted into the second grooves when the positioning cover is disposed at the second position.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of Taiwanese Application No. 102218302,filed on Sep. 27, 2013.

BACKGROUND OF THE INVENTION

1. Field of the invention

This invention relates to an optical fiber connector, more particularlyto a duplex optical fiber connector including a positioning cover formedwith a pair of first grooves and a pair of second grooves forrespectively positioning end sleeves of two terminal plugs.

2. Description of the related art

U.S. Pat. No. 8,152,385 discloses a conventional duplex fiber opticconnector for connecting optical fibers of a fiber optic cable to anadapter of a work station. The conventional duplex fiber optic connectorhas a switchable polarity, and includes a housing, first and secondfiber optic connector assemblies that have different polarityconfigurations, and a removable trigger mechanism. The first and secondfiber optic connector assemblies have tubular end sleeves, and areconnected to and receive the optical fibers of the fiber optic cable,respectively. The housing defines a pair of parallel apertures thatreceive the tubular end sleeves of the first and second fiber opticconnector assemblies, respectively, such that the first and second fiberoptic connector assemblies are positioned in the parallel apertures andare rotatable relative to the housing for polarity reversal. Theremovable trigger mechanism is slidably and detachably sleeved on thehousing to engage releasably the first and second fiber optic connectorassemblies so as to prevent rotation of the first and second fiber opticconnector assemblies relative to the housing, and in turn, undesiredpolarity reversal. The polarity reversal is accomplished by removing theremovable trigger mechanism from the housing, followed by rotating thefirst and second fiber optic connector assemblies and re-installing theremovable trigger mechanism on a reverse side of the housing.

Although the conventional duplex fiber optic connector can provide thepolarity reversal function, it has a fixed pitch (such as a 5.25 mmpitch or a 6.25 mm pitch) between longitudinal axes of the first andsecond fiber optic connector assemblies that is only suitable for anadapter having a corresponding pitch, and is unable to be used foradapters with different pitches. As such, system centers, such as datacommunication centers, computer centers, information centers and thelike, are required to store various fiber optic connectors withdifferent pitches, which increases burden in inventory stock, storagespace and associated costs.

SUMMARY OF THE INVENTION

Therefore, the object of the present invention is to provide an opticalfiber connector that can overcome the aforesaid drawback associated withthe prior art.

According to the present invention, there is provided an optical fiberconnector adapted to be connected to at least two optical fibers. Theoptical fiber connector comprises: a positioning housing for extensionof the optical fibers therethrough and having a recessed open end; apositioning cover having first and second axial ends and an inner sidethat extends between the first and second axial ends and that is formedwith at least two first grooves and at least two second grooves forpositioning and extension of the optical fibers therein, the first andsecond axial ends being opposite to each other in an axial direction,the first grooves being aligned with each other along a transversedirection transverse to the axial direction, the second grooves beingaligned with each other along the transverse direction, each of thefirst grooves being spaced apart from and partially overlapping acorresponding one of the second grooves along the axial direction; andat least two terminal plugs, each of which has a plug housing and an endsleeve connected to the plug housing in the axial direction forsequential extension of a corresponding one of the optical fibers the rethrough. The positioning cover is detachably mountable on thepositioning housing between first and second positions relative to thepositioning housing to cover the recessed open end of the positioninghousing. When the positioning cover is disposed at the first position,the first grooves are respectively disposed between the plug housings ofthe terminal plugs and the second grooves along the axial direction andthe end sleeves of the terminal plugs are respectively fitted into thefirst grooves. When the positioning cover is disposed at the secondposition, the second grooves are respectively disposed between the plughousings and the first grooves along the axial direction and the endsleeves are respectively fitted into the second grooves.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will becomeapparent in the following detailed description of the preferredembodiments with reference to the accompanying drawings, of which:

FIG. 1 is a perspective view of the first preferred embodiment of anoptical fiber connector according to the present invention;

FIG. 2 is an exploded perspective view illustrating a state where apositioning cover is removed from a positioning housing of the firstpreferred embodiment;

FIG. 3 is a perspective view of the positioning cover of the firstpreferred embodiment;

FIG. 4 is a perspective view illustrating a state where a tighteningsleeve is removed from the positioning cover and the positioning housingof the first preferred embodiment and where the positioning cover isdisposed at a first position;

FIG. 5 is a perspective view illustrating another state where thepositioning cover of the first preferred embodiment is disposed at asecond position;

FIG. 6 is a perspective view illustrating a state where the positioningcover is disposed at the first position for receiving a pair of terminalplugs of the first preferred embodiment;

FIG. 7 is a perspective view illustrating another state where thepositioning cover is disposed at the second position for receiving thepair of terminal plugs of the first preferred embodiment;

FIGS. 8 to 11 are perspective views illustrating consecutive steps of aprocess of performing polarity reversal of the terminal plugs of thefirst preferred embodiment;

FIGS. 12 and 13 are schematic views illustrating consecutive steps ofperforming simultaneous rotation of the terminal plugs of the firstpreferred embodiment; and

FIG. 14 is a schematic sectional view of the second preferred embodimentof the optical fiber connector according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before the present invention is described in greater detail withreference to the accompanying preferred embodiments, it should be notedherein that like elements are denoted by the same reference numeralsthroughout the disclosure.

FIGS. 1 to 3 illustrate the first preferred embodiment of an(multi-fiber) optical fiber connector according to the presentinvention.

The optical fiber connector is adapted to be connected to at least twooptical fibers 2A, 2B of a fiber optic cable 200 and an adapter of anequipment (not shown), such as a work station, and includes apositioning housing 4, a positioning cover 3, a tightening sleeve 5, andat least two terminal plugs 10A, 10B. A boot 6 is secured to the fiberoptic cable 200.

The positioning housing 4 is for the optical fibers 2A, 2B to extendtherethrough, and has a hollow block body 400 that has first and secondaxial ends 401, 402, an extension wall 45 that extends in an axialdirection (X) from the first axial end 401 of the block body 400 towardthe terminal plugs 10A, 10B, and that cooperates with the first axialend 401 to define a recessed open end 41, and a tubular tail 42 thatextends in the axial direction (X) from the second axial end 402 of theblock body 400 toward the boot 6. The boot 6 is sleeved on the tubulartail 42. In this embodiment, the recessed open end 41 has a generallyL-shaped structure.

The positioning cover 3 has first and second axial ends 301, 302, aninner side 30, and an outer side 35 opposite to the inner side 30 in avertical direction (Y) that is transverse to the axial direction (X).The inner side 30 extends between the first and second axial ends 301,302 of the positioning cover 3, and is formed with at least two firstgrooves 31A, 31B and at least two second grooves 32A, 32B forpositioning and extension of the optical fibers 2A, 2B therein. Thefirst and second axial ends 301, 302 of the positioning cover 3 areopposite to each other in the axial direction (X). The first grooves31A, 31B are aligned with each other along a transverse direction (Z)transverse to the axial direction (X) and the vertical direction (Y).The second grooves 32A, 32B are aligned with each other along thetransverse direction (Y). Each of the first grooves 31A, 31B is spacedapart from and partially overlaps a corresponding one of the secondgrooves 32A, 32B along the axial direction (X).

Each of the terminal plugs 10A, 10B has a plug housing 15A, 15B forextension of a corresponding one of the optical fibers 2A, 2Btherethrough, an optical ferrule 20A, 20B that protrudes from a firstend 151 of the plug housing 15A, 15B in the axial direction (X) and thatis connected to the corresponding one of the optical fibers 2A, 2B, andan end sleeve 13A, 13B that is disposed opposite to the optical ferrule20A, 20B in the axial direction (X) and that extends from a second end152 of the plug housing 15A, 15B in the axial direction (X) away fromthe optical ferrule 20A, 20B for extension of the corresponding one ofthe optical fibers 2A, 2B therethrough. In this embodiment, the plughousings 15A, 15B of the terminal plugs 10A, 10B are rectangular cuboidsin shape.

The positioning cover 3 is detachably mountable on the positioninghousing 4 between first and second positions (see FIGS. 4 and 5)relative to the positioning housing 4 to cover the recessed open end 41of the positioning housing 4. When the positioning cover 3 is disposedat the first position, the first grooves 31A, 31B are respectivelydisposed between the plug housings 15A, 15B of the terminal plugs 10A,10B and the second grooves 32A, 32B along the axial direction (X) andthe end sleeves 13A, 13B are respectively fitted into the first grooves31A, 31B (see FIG. 6). When the positioning cover 3 is disposed at thesecond position, the second grooves 32A, 32B are respectively disposedbetween the plug housings 15A, 15B and the first grooves 31A, 31B alongthe axial direction (X) and the end sleeves 13A, 13B are respectivelyfitted into the second grooves 32A, 32B (see FIG. 7).

In this embodiment, the inner side 30 of the positioning cover 3 isfurther formed with a middle groove 36 that is disposed between and thatseparates the first grooves 31A, 31B and the second grooves 32A, 32Balong the axial direction (X). The end sleeve 13A, 13B of each of theterminal plugs 10A, 10B has a tubular portion 131 that extends and thatis reduced in dimension from the second end 152 of the plug housing 15A,15B in the axial direction (X), and a head portion 132 that is connectedto and enlarged in diameter from the tubular portion 131. The tubularportions 131 of the end sleeves 13A, 13B are respectively fitted intothe first grooves 31A, 31B when the positioning cover is disposed at thefirst position, and are respectively fitted into the second grooves 32A,32B when the positioning cover 3 is disposed at the second position. Thehead portions 132 of the end sleeves 13A, 13B extend into the middlegroove 36 when the positioning cover 3 is disposed at the first andsecond positions (see FIGS. 6 and 7), thereby limiting axial movement ofthe terminal plugs 10A, 10B.

The first axial end 301 of the positioning cover 3 is distal from thefirst axial end 401 of the block body 400 and the second axial end 302of the positioning cover 3 covers and contacts the first axial end 401of the block body 400 when the positioning cover 3 is disposed at thefirst position (see FIG. 4). The second axial end 302 of the positioningcover 3 is distal from the first axial end 401 of the block body 400 andthe first axial end 301 of the positioning cover 3 covers and contactsthe first axial end 401 of the block body 400 when the positioning cover3 is disposed at the second position (see FIG. 5). The inner side 30 ofthe positioning cover 3 covers and contacts the extension wall 45 whenthe positioning cover 3 is disposed at the first and second positions.

The outer side 35 of the positioning cover 3 is formed with first andsecond recesses 33, 34 which extend axially and respectively from thefirst and second axial ends 301, 302 of the positioning cover 3, andtoward each other. The block body 400 has two opposite U-shaped sidewalls 403 that are opposite to each other in the transverse direction(Z) and that extend from the first axial end 401 of the block body 400to the second axial end 402 of the block body 400, an arc-shaped bottomwall 404 that is connected to the extension wall 45 in the axialdirection (X) and that interconnects the U-shaped side walls 403, and anarc-shaped top wall 405 that extends from the first axial end 401 of theblock body 400 to the second axial end 402 of the block body 400 andthat interconnects the U-shaped side walls 403. The block body 400 isformed with a tongue 43 that protrudes from the first axial end 401thereof toward the terminal plugs 10A, 10B. The tongue 43 is fitted intothe second recess 34 when the positioning cover 3 is disposed at thefirst position (see FIG. 4), and is fitted into the first recess 33 whenthe positioning cover 3 is disposed at the second position (see FIG. 5).The block body 400 defines a positioning channel 410 therein forextension of the optical fibers 2A, 2B therethrough, and is furtherformed with an axial wall slit 40 that is in spatial communication withthe positioning channel 410 and that extends through the top wall 405and the tongue 43 of the block body 400 for allowing elastic deformationof the block body 400 in the transverse direction (Z).

The tightening sleeve 5 is slidably and tightly sleeved on thepositioning housing 4 and the positioning cover 3 for securing thepositioning cover 3 to the positioning housing 4 and for securing andmaintaining axial and lateral alignment of the terminal plugs 10A, 10Bthrough constriction of the positioning cover 3 and the block body 400by an elastic force provided by the tightening sleeve 5. The tighteningsleeve 5 has a closed loop-shaped frame body 500 that defines a framespace 50 for receiving the positioning housing 4 and the positioningcover 3 therein, and a spring pressing arm 51 that extends outwardly andinclinedly from the frame body 500 and that has a hooked end 511. Eachof the terminal plugs 10A, 10B further has a spring latch arm 12 thatextends outwardly and inclinedly from the plug housing 15A, 15B. Thespring latch arm 12 of each of the terminal plugs 10A, 10B has a hookedend 121 that releasably engages the hooked end 511 of the springpressing arm 51, and a middle shoulder 120 that is adapted to engagereleasably the adapter of the work station (not shown) when the terminalplugs 10A, 10B are inserted into the slot in the adapter in apredetermined insertion direction. The spring pressing arm 51 abutsagainst the spring latch arms 12 of the terminal plugs 10A, 10B formanually pressing the latter to move downwardly to allow disengagementbetween the terminal plugs 10A, 10B and the adapter and removal of theterminal plugs 10A, 10B out of the slot. The frame body 500 has twoopposite U-shaped side walls 503 and two opposite arc-shaped middlewalls 504 that interconnect the U-shaped side walls 503 and that areopposite to each other in the vertical direction (Y). Each of theU-shaped side walls 403 of the block body 400 conforms to an adjacentone of the U-shaped side walls 503 of the frame body 500, and thearc-shaped top wall 405 of the block body 400 conforms to an adjacentone of the arc-shaped middle walls 504 of the frame body 500 when thetightening sleeve 5 is sleeved tightly on the positioning housing 4.

Each of the first grooves 31A, 31B is defined by a corresponding firstU-shaped wall 37A, 37B. Each of the second grooves 32A, 32B is definedby a corresponding second U-shaped wall 38A, 38B. Each of the first andsecond U-shaped walls 37A, 37B, 38A, 38B has a semi-circular wallportion 319, 329. The semi-circular wall portions 319 of the firstU-shaped walls 37A, 37B of the first grooves 31A, 31B respectivelydefine first axes S1. The semi-circular wall portions 329 of the secondU-shaped walls 38A, 38B of the second grooves 32A, 32B respectivelydefine second axes S2 parallel to the first axes S1. The first axes S1are disposed between and are spaced apart from the second axes S2 alongthe transverse direction (Z). The tubular portions 131 of the endsleeves 13A, 13B are respectively and coaxially disposed on thesemi-circular wall portions 319 of the first U-shaped walls 37A, 37Bwhen the positioning cover 3 is disposed at the first position. The thetubular portions 131 of the end sleeves 13A, 13B are respectively andcoaxially disposed on the semi-circular wall portions 329 of the secondU-shaped walls 38A, 38B when the positioning cover 3 is disposed at thesecond position. When the positioning cover 3 is disposed at the firstposition, the first axes S1 respectively overlap axes of the terminalplugs 10A, 10B. When the positioning cover 3 is disposed at the secondposition, the second axes S2 respectively overlap the axes of theterminal plugs 10A, 10B.

To change a pitch (P) between the axes of the terminal plugs 10A, 10Bfrom 5.25 mm as shown in FIGS. 6 to 6.25 mm as shown in FIG. 7, thespring latch arms 12 are disengaged from the spring pressing arm 51first, followed by removing the tightening sleeve 5 from the positioninghousing 4 and the positioning cover 3, removing the positioning cover 3from the positioning housing 4, re-mounting the positioning cover 3 onthe position housing 4 such that the positioning cover 3 is disposed atthe second position, re-tightening the positioning housing 4 and thepositioning cover 3 with the tightening sleeve 5, and re-engaging thespring latch arms 12 with the spring pressing arm 51.

The terminal plugs 10A, 10B are rotatable relative to the positioninghousing 4 when the positioning cover 3 is positioned at the first andsecond positions, thereby permitting polarity reversal of the terminalplugs 10A, 10B.

FIGS. 8 to 11 illustrate consecutive steps of a process of performingthe polarity reversal of the terminal plugs 10A, 10B which carry theoptical fibers 2A, 2B (see FIGS. 2 and 5). In operation, the springlatch arms 12 are disengaged from the spring pressing arm 51 first,followed by removing the tightening sleeve 5 from the positioninghousing 4 and the positioning cover 3 (see FIG. 8), rotating each of thetightening sleeve 5 and the terminal plugs 10A, 10B by 180 degreesrelative to the positioning housing 4 and the positioning cover 3 (seeFIG. 9), rotating the optical fiber connector by 180 degrees (see FIG.10) so that the spring latch arms 12 and the spring pressing arm 51 faceupwardly (the predetermined insertion direction for allowing subsequentinsertion of the terminal plugs 10A, 10B into the slot in the adapter)and that the positioning cover 3 faces downwardly, re-tightening thepositioning housing 4 and the positioning cover 3 with the tighteningsleeve 5 (see FIG. 11), and re-engaging the spring latch arms 12 withthe spring pressing arm 51 (see FIG. 11). Alternatively, the opticalfiber connector may be rotated by 180 degrees after the tightening ofthe positioning housing 4 and the positioning cover 3 with thetightening sleeve 5 and/or after the engagement between the spring latcharms 12 and the spring pressing arm 51.

Referring to FIGS. 12 and 13, the plug housings 15A, 15B have the samestructure, and each of the plug housings 15A, 15B has a square peripherywith a diagonal distance (or a maximum width) and four sides that have aside length, such that the pitch (P) between the axes of the plughousings 15A, 15B is at least greater than the summation of a half ofthe diagonal distance and a half of the side length, thereby preventinginterference between the plug housings 15A, 15B when each plug housing15A, 15B is rotated 180 degrees relative to the positioning housing 4from a first polarity configuration (see FIG. 12) to a second polarityconfiguration (not shown). It is noted that the plug housings 15A, 15Bmay be rotated 180 degrees relative to the positioning housing 4 oneafter the other or simultaneously. To facilitate simultaneous rotationsof the plug housings 15A, 15B relative to the positioning housing 4, thepitch (P) between the axes of the plug housings 15A, 15B is at leastgreater than the diagonal distance of the square periphery of the plughousing 15A, 15B (see FIG. 13 when the plug housings 15A, 15B are bothrotated by 45 degrees).

FIG. 14 illustrates the second preferred embodiment of the optical fiberconnector according to the present invention. The second preferredembodiment differs from the previous embodiment in that the U-shapedside walls 503 of the frame body 500 of the tightening sleeve 5 arefurther tightly and releasably fitted on the plug housings 15A, 15B,respectively, in addition to being sleeved on the positioning housing 4(see FIG. 2) and the positioning cover 3 (see FIG. 2), when thepositioning cover 3 is disposed at the second position.

With the inclusion of the positioning housing 4 and the positioningcover 3 in the optical fiber connector of this invention and by formingthe first grooves 31A, 31B and the second grooves 32A, 32B in thepositioning cover 3, the aforesaid drawback associated with the priorart may be eliminated.

While the present invention has been described in connection with thatare considered the most practical and preferred embodiments, it isunderstood that this invention is not limited to the disclosedembodiments but is intended to cover various arrangements includedwithin the spirit and scope of the broadest interpretation so as toencompass all such modifications and equivalent arrangements.

What is claimed is:
 1. An optical fiber connector adapted to beconnected to at least two optical fibers, said optical fiber connectorcomprising: a positioning housing for extension of the optical fiberstherethrough and having a recessed open end; a positioning cover havingfirst and second axial ends and an inner side that extends between saidfirst and second axial ends and that is formed with at least two firstgrooves and at least two second grooves for positioning and extension ofthe optical fibers therein, said first and second axial ends beingopposite to each other in an axial direction, said first grooves beingaligned with each other along a transverse direction transverse to saidaxial direction, said second grooves being aligned with each other alongsaid transverse direction, each of said first grooves being spaced apartfrom and partially overlapping a corresponding one of said secondgrooves along said axial direction; and at least two terminal plugs,each of which has a plug housing and an end sleeve connected to saidplug housing in said axial direction for sequential extension of acorresponding one of the optical fibers therethrough; wherein saidpositioning cover is detachably mountable on said positioning housingbetween first and second positions relative to said positioning housingto cover said recessed open end of said positioning housing; whereinwhen said positioning cover is disposed at said first position, saidfirst grooves are respectively disposed between said plug housings ofsaid terminal plugs and said second grooves along said axial directionand said end sleeves of said terminal plugs are respectively fitted intosaid first grooves; and wherein when said positioning cover is disposedat said second position, said second grooves are respectively disposedbetween said plug housings and said first grooves along said axialdirection and said end sleeves are respectively fitted into said secondgrooves.
 2. The optical fiber connector of claim 1, wherein said innerside of said positioning cover is further formed with a middle groovethat is disposed between said first grooves and said second groovesalong said axial direction, each of said end sleeves having a tubularportion that extends from said plug housing in said axial directiontoward said positioning housing, and a head portion that is enlarged indiameter from said tubular portion and that is distal from said plughousing, said tubular portions of said end sleeves being respectivelyfitted into said first grooves when said positioning cover is disposedat said first position, and being respectively fitted into said secondgrooves when said positioning cover is disposed at said second position,said head portions of said end sleeves extending into said middle groovewhen said positioning cover is disposed at said first and secondpositions.
 3. The optical fiber connector of claim 1, wherein saidpositioning housing has a hollow block body that has an axial end, andan extension wall that extends in said axial direction from said axialend toward said terminal plugs and that cooperates with said axial endto define said recessed open end of said positioning housing, saidrecessed open end having a generally L-shaped structure, said secondaxial end of said positioning cover covering and contacting said axialend of said block body when said positioning cover is disposed at saidfirst position, said first axial end of said positioning cover coveringand contacting said axial end of said block body when said positioningcover is disposed at said second position, said inner side of saidpositioning cover covering and contacting said extension wall when saidpositioning cover is disposed at said first and second positions.
 4. Theoptical fiber connector of claim 3, wherein said positioning coverfurther has an outer side that is opposite to said inner side in avertical direction and that is formed with first and second recesseswhich extend along said axial direction respectively from said first andsecond axial ends of said positioning cover and toward each other, saidvertical direction being transverse to said axial direction and saidtransverse direction, said block body being formed with a tongue thatprotrudes along said axial direction from said axial end of said blockbody toward said terminal plugs, said tongue being fitted into saidsecond recess when said positioning cover is disposed at said firstposition, and being fitted into said first recess when said positioningcover is disposed at said second position.
 5. The optical fiberconnector of claim 3, wherein said block body defines a positioningchannel therein for extension of the optical fibers therethrough, and isformed with an axial wall slit that is in spatial communication withsaid positioning channel for allowing elastic deformation of said blockbody in said transverse direction.
 6. The optical fiber connector ofclaim 5, further comprising a tightening sleeve that is slidably andtightly sleeved on said positioning housing and said positioning coverfor securing said positioning cover to said positioning housing.
 7. Theoptical fiber connector of claim 6, wherein said tightening sleeve has aframe body and a spring pressing arm that extends outwardly from saidframe body, each of said terminal plugs further having a spring latcharm that extends outwardly from said plug housing and that releasablyengages said spring pressing arm.
 8. The optical fiber connector ofclaim 1, wherein each of said first grooves is defined by a firstU-shaped wall, each of said second grooves being defined by a secondU-shaped wall, each of said first and second U-shaped walls having asemi-circular wall portion, said semi-circular wall portions of saidfirst U-shaped walls respectively defining first axes, saidsemi-circular wall portions of said second U-shaped walls respectivelydefining second axes, said first axes being disposed between and beingspaced apart from said second axes along said transverse direction. 9.The optical fiber connector of claim 1, wherein said terminal plugs arerotatable relative to said positioning housing when said positioningcover is positioned at said first and second positions, therebypermitting reversal of said terminal plugs.
 10. The optical fiberconnector of claim 7, wherein said block body has two U-shaped sidewalls that are opposite to each other in said transverse direction andan arc-shaped top wall that interconnects said U-shaped side walls, saidframe body having two U-shaped side walls that are opposite to eachother in said transverse direction, and two arc-shaped middle walls thatinterconnect said U-shaped side walls of said frame body and that areopposite to each other in a vertical direction transverse to said axialdirection and said transverse direction, each of said U-shaped sidewalls of said block body conforming to an adjacent one of said U-shapedside walls of said frame body and said arc-shaped top wall of said blockbody conforming to an adjacent one of said arc-shaped middle walls ofsaid frame body when said tightening sleeve is sleeved tightly on saidpositioning housing.
 11. The optical fiber connector of claim 10,wherein said U-shaped side walls of said frame body are tightly andreleasably fitted on said plug housings, respectively, when saidpositioning cover is disposed at said second position.